1. Field of the Invention
This invention generally relates to apparatus for digging ditches and trenches. This invention particularly relates to apparatus having a continuous chain to which excavating elements are secured, the chain and excavating elements being suitable for removing hard soils and rock to form a ditch or trench. This invention more particularly relates to track elements secured to a continuous chain that permit a more desirable distribution of cutting or mining teeth that will provide for superior performance of a trencher using such track elements.
2. Background of the Invention
A commonly used type of chain ditcher is characterized by an elongated boom mounted on a supporting structure such as a tractor. The boom is pivoted to the tractor and is provided at both ends with one or more sprockets, around which a heavy chain passes. Plates are bolted to the links of the heavy chain. Sockets are welded to the plates in a more or less orderly pattern such that when cutting teeth are placed in the sockets, the cutting surfaces of the teeth will cover substantially the entire width of the ditch to be dug at least once in a complete revolution of the chain around the boom. Rotation of the chain as the boom is lowered causes the cutting teeth to abrade and chip away the material in front of the chain until the boom reaches the desired depth and cutting angle. The bottom of the ditch is generally cut by the cutting surfaces of the teeth on each plate as the plate rounds the end of the boom. The entire unit is then moved slowly forward so that the ditch is elongated at full depth in the direction taken by the tractor. As the unit is moved forward, the cutting surfaces of the teeth on the plates bolted to the chain engage substantially the entire face of ditch. Of course, only the tooth points actually touch the face of the ditch, but all the points on the chain along the entire face of the ditch are being advanced at the rate of the advance of the tractor, therefore, all the points are sharing approximately equal parts of the total effort available to rotate the chain and to advance the chain against the face of the ditch.
Each tooth scours a substantially linear path up the face of the ditch as the chain is rotated by the sprockets. With sufficient contact pressure, the teeth penetrate into the soil and rock to chip and route spoil from the face of the ditch and the ditching is accomplished at a meaningful rate. Chips and other spoil materials are lifted out of the ditch by the drag and impact forces imparted in an upward direction along the face of the ditch by the rapid rotation of the chain. It is important that the teeth be evenly distributed to assure an efficient ripping and cutting action on the ditch face. However, in some equipment, the bolts securing the plates to the chain prohibit the use of some locations for sockets to receive the cutting teeth. Consequently, the sockets are often situated in undesirable locations forward and rearward of the midline of each supporting plate, and twisted or angled in an attempt to locate the tooth points at the desired location. The forward and rearward displacement of the cutting teeth on each plate causes an unintended change in cutting angle at the very bottom of the trench or ditch. Further, this twisting and angling of the sockets results in the teeth being presented at an incorrect or awkward cutting angle even on the ditch face that can contribute to uneven tooth wear and can slow down the trenching process. Additionally, any portion of the bolts securing the plates to the chain that protrude above the outer surface of the plates is subjected to abrasive wear by the spoil materials.
Thus, there remains a need for a trencher track that can allow for the uniform positioning and angling of the tooth holding sockets so that an optimum cutting action can be achieved and the teeth life sustained for a longer period of time. There also remains a need for tooth holding sockets that can be fixed to the outer surface of the trencher track at any desired location while reliably retaining the desired cutting attack angle.